1. Field of the Invention
The present invention relates to ozone generation systems, and more particularly to a system and method for generating and dispersing ozone in a fluid, such as water, for use in a wide variety of process applications.
2. Description of the Background Art
Ozone is a naturally occurring oxygen compound designated as O.sub.3. Ozone may be generated when oxygen, O.sub.2, is exposed to ultraviolet light or an electrical charge which breaks the oxygen down to individual oxygen molecules, which combine to form ozone molecules. Ozone is an unstable, powerful bleaching and oxidizing agent with a pungent irritating odor and is used to purify and deodorize air, to sterilize water, and as a bleaching agent. At the appropriate elevated concentrations, ozone may be used as a sterilizing agent to control airborne organics, molds, fungus, bacteria, and viruses. Accordingly, ozone has been recognized as useful as a disinfectant in a variety of applications. For example, it is known to use ozone in hospital operating rooms, laundry and disposal rooms, in food service applications, in hotels, restaurants, and livestock industries. Furthermore, ozone has proven effective as a bleaching and sterilizing agent in water and has been found to be particularly effective, at appropriate elevated concentration levels, in laundry water.
Typical prior art ozone generators utilize ambient air as a feed gas for the production of ozone. However, there are a number of significant disadvantages in using ambient air to produce ozone. Specifically, since the production of ozone is largely dependent upon the humidity, temperature, contamination and oxygen content of the ambient air, and further because of the abundance of nitrogen in ambient air (ambient air consists of approximately 75% nitrogen and 25% oxygen), prior art ozone generators using ambient air as a feed gas produce inconsistent amounts of ozone. Furthermore, generating ozone in the presence of nitrogen results in the production of nitrous oxides, resulting in the formation of nitric acid often within the ozone generator thereby leading to substantial corrosion problems. Such nitric acid in the ozone generator can, because of its conductive properties, reduce the efficiency of the equipment, and can severely corrode the equipment resulting in a further loss of ozone production efficiency and often irreversible damage to the equipment. In addition, in applications involving the dispersal of ozone in water, the nitric acid byproduct presents a corrosion problem for all downstream system components.
The use of ozone in laundry applications is recognized in the background art. U.S. Pat. No. 5,097,556, issued to Engel et al. discloses a method for washing laundry without hot water and detergent using a closed loop ozonated wash water system wherein wash water maintained in a storage tank is ozonated by an ozone generator prior to use in a washing machine. Engel et al. discloses the use of a submerged ozone injection nozzle spaced from a motor driven impeller for mixing the ozone within water held in a holding tank. The use of a conventional impeller spaced from a submerged ozone injection nozzle has been found not to efficiently mix ozone in water. In addition, Engel et al. uses a plurality of pumps and manufactures ozone from ordinary ambient air.
U.S. Pat. No. 5,409,616, issued to Garbutt et al., discloses a method and apparatus to restore grey water resulting from a cleaning activity such as laundry using ozone as a cleaning agent. Garbutt et al. disclose a process whereby ozone is manufactured from a high purity oxygen feed gas produced utilizing molecular sieves to remove a substantial amount of the nitrogen present in ambient air. Garbutt et al. further discloses a static mixer consisting of a series of spiral blades fitted inside a section of pipe immediately downstream of the ozone injection point. The spiral blades cause a counter-rotating flow of water within the pipe section to improve the mixing effect. According to Garbutt et al., the static mixer effectively blends the ozone and water and allows for a greater volume of ozone to be introduced into a given volume of water. However, since the Garbutt et al. static mixing blades are fixed, blending effectiveness is at best only marginally enhanced.
A further significant aspect relating to the use of ozone in fluids, such as water, involves monitoring and controlling ozone concentration. Neither the Engel et al. reference, nor the Garbutt et al. reference disclose a system or method for monitoring and controlling the concentration of ozone in water. Furthermore, prior art ozone generating devices have heretofore only been capable of producing an ozonated gas stream comprising approximately 1%-2% ozone by weight.
Accordingly there exists a need for a system and method for generating and dispersing ozone in a fluid for use as a cleaning or sterilizing agent, which system effectively produces a large quantity of ozone from a highly pure oxygen feed gas, effectively blends large quantities of ozone in a given volume of water, and is capable of precisely monitoring and controlling the concentration of ozone.